If a policeman sees a felon fleeing a serious crime, he is legally allowed to use a gun to stop the perpetrator. However, if the criminal is running through a crowd, the lawman may not shoot, because it is not legal to endanger civilians in pursuit of a criminal.
Likewise, if a certain apartment in a block of flats is known to be a manufacturing and distribution site for illegal drugs, it is not considered acceptable to bomb it, knowing that adjacent flats, if not the whole building, wil be destroyed.
Why the double standard? Why is it OK to do exactly these things in Baghdad but not in New York?
I think the 9/11 attack on the WTC should have been handled the same way the previous WTC attack was handled.
The fact is, the 9/11 attack was merely a convenient excuse for implementing a larger, imperialistic agenda.
As far as the British vs the American approach to both 'peacekeeping' and law enforcement, I would say the current American strategy is one of hyper-aggressiveness, AKA: Shock and Awe.
This is not just a military strategem. It permeates the whole society. One only has to watch a few episodes of American reality cop shows like "Cops" to see that hyperaggressive overkill is the order of the day.
Compare Cops to arrest scenes in old movies and the new approach is clear.